Dosage-dispensing devices are generally used for the purpose of dispensing small, precisely measured quantities of critical, for example toxic, substances into a target vessel. The latter is normally set on a balance, so that the weight of the dispensed substance can be monitored during the dispensing process and the further discharge of substance into the target vessel can be stopped when the target weight has been reached.
Instruments of the current state of the art such as for example the dosage-dispensing device described in commonly-owned EP 1930702 A1 (also available as U.S. Pat. No. 8,245,883 B2) are characterized by a two-part design structure with, on the one hand, a control unit or base unit and on the other hand a dispensing unit, which can be installed in a receiving- or holding device of the base unit in such a way that the dispensing unit can easily be taken out and exchanged. The dispensing unit, which contains a supply of the substance to be dispensed, includes at least a dispensing head with a discharge orifice and with component elements that serve to open and close the discharge orifice, as well as in certain cases to propel and loosen the powderous or pasteous dosage material. As a further constituent part of the dispensing unit, a source container can be connected to the dispensing head for the purpose of accommodating a bigger supply volume.
The control unit in the dosage-dispensing device of EP 1930702 A1 is a stationary base- or console unit which is set up on a work surface. In the operating state, the discharge orifice of the installed dispensing unit is directed downward, and the means for opening and closing the discharge orifice as well as, in certain cases, for propelling and loosening the powderous or pasteous dosage material are in releasable engagement with propulsion- or actuation elements that are part of the control unit. The dispensing unit in its installed state in the control unit is arranged in a laterally projecting part of the control unit, so as to provide space for a balance below the dispensing unit. For further details, the reader is referred to the European patent application EP 1930702 A1, whose disclosure content in its entirety is hereby incorporated by reference in the present description.
In the dosage-dispensing device described in EP 1930702 A1, the functions of advancing and loosening the powderous or pasteous dosage material are performed through the stirring action of a stirring mechanism in the dispensing head and, in certain cases, a second stirring mechanism in the source container. A further dosage-dispensing device, which is described in commonly-owned EP 1959244 B1 (also available as U.S. Pat. No. 8,191,587 B2), shows the same design structure with a base unit on which an exchangeable dispensing unit is installed. However, the functions of propelling and loosening the dosage material are in this case achieved by imparting shocks to the dispensing unit. The control unit is equipped for this purpose with an impact mechanism, i.e. in essence a hammer mechanism. This solution proves to be particularly advantageous for certain powderous dosage materials such as for example corn starch, which would be compacted by stirring instead of being loosened, so that the flow of material through the dispensing head would be blocked and, as a consequence, no material could be discharged from the dispensing head even with the discharge orifice fully opened. For further details of this dosage-dispensing device with an impact mechanism, the reader is referred to EP 1959244 B2, which is hereby incorporated by reference as if fully recited herein.
Further details and variations of the state of the art, specifically in regard to the dispensing head, can be found in commonly-owned EP 2088404 A1 (also available as U.S. Pat. No. 8,281,959 B2). Among other things, a dispensing head is described wherein the area of the discharge orifice consists of an elastic material, so that the for example slit-shaped orifice can be spread apart through mechanical action, and closed again by removing the mechanical action. In addition, different embodiments of propelling means are presented, as well as designs of the inside which complement the propelling means.
All of the examples of the state of the art named above are characterized by the aforementioned two-part structure with a base/control unit and a dispensing unit that can be installed in the base unit. The ease of installing and removing or exchanging the dispensing unit is a particularly important aspect. A receiving device which is connected to the base unit and in which the dispensing unit can be seated and safely secured is described in commonly-owned EP 1959243 B1 (also available as U.S. Pat. No. 8,042,711 B2).
In each of the dosage-dispensing devices of the state of the art the dispensing unit, which can include the dispensing head by itself or a dispensing head with an attached source container, is designed for long-term, repetitive use, i.e. as a unit which can be refilled again and again with the same or a different dosage substance and which can also be cleaned in between.
In practice, however, a still unmet need has been discovered for a favorably priced, compact dispensing unit, preferably consisting of the dispensing head alone, which can be used, for example, for a small number of dispensing cycles with the same substance and which can subsequently be discarded with the left-over substance remaining inside it. A dispensing unit of this kind offers strong advantages in particular for the dispensing of toxic substances.
It is therefore the object of this invention to provide a dispensing head which can be used as part of a dosage-dispensing device of the kind described for example in EP 1930702 A1 for the dispensing of free-flowing powderous and pasteous substances. The dispensing head should be configured in particular for small fill quantities (typically less than two grams), and its manufacturing cost should be low enough that it could be discarded after use as a consumable supply article.